The present invention relates to an aircraft structure, and more particularly to an aircraft fuselage structure made of fiber-reinforced resin. The invention also relates to a method of fabricating the fuselage structure.
Various techniques or methods for fabricating aircraft fuselage structures by using fiber-reinforced resins have been proposed in the prior art.
In one such method, a framework comprising longitudinal stringers and reinforcing rings is sub-assembled beforehand in a separate process. An inner mold is placed in this framework. On the other surface of the inner mold on which the framework is fitted, exposed fibers and outer sheathing fibers are alternately laminated with a resin interposed therebetween. A hollow cylindrical structure is thus formed as disclosed in Japanese Patent Application Laid-Open Publication No. 61-169394.
According to another method, reinforcing fibers impregnated with adhesive are prepared. The reinforcing fibers are laminated by stretching on a convex molding surface of a split male mold half. The adhesive is then set or hardened thereby to form a fiber laminated structure of the shape of a split hollow cylinder. The thus obtained structure is then interwoven. Thereafter the adhesive thereof is removed. The resulting fiber laminated structure is then placed in a split female mold half and is impregnated with a resin. The resin is then set thereby to fabricate an outer sheathing of the shape of a split hollow cylinder half. Two of the outer sheathings are joined together in a manner such that the exposed reinforcing fibers become intertwined. The fiber-intertwined parts thus formed are impregnated with a resin. The resin is set, whereupon an outer skin structure is obtained. The method is disclosed in Japanese Patent Application Laid-Open Publication No. 62-19440.
According to a known method of mutually connecting together members constituting a fuselage, fibers orientated in two mutually perpendicular directions are interwoven to form a criss-crossing fabric. The criss-crossing fabric is used at the connections and impregnated with a resin. By setting the resin, strong connections are produced. The method is disclosed in Japanese Patent Application Laid-Open Publication No. 57-34944.
The methods known in the prior art, however, have been accompanied by problems as described below.
In the first method described above, it is necessary to fabricate beforehand longitudinal stringers and reinforcing rings to become strength members for a fuselage. This lowers production efficiency. Furthermore, in order to connect the rings and the outer skin, the exposed fibers of the ring outer surfaces and the outer skin fibers must be alternately laminated with a resin interposed therebetween. The work efficiency is therefore poor. Also the quality of the product formed by the method is not fully satisfactory.
According to the second method described above, during the forming of the outer skin structure of split hollow cylindrical half, lamination is first carried out together with the adhesive. Thereafter the adhesive is removed. Then the skin must be newly impregnated with a resin. These steps require much laborious work.
In the third method described above, in order to mutually connect together members constituting a fuselage, other members are necessary. This results in additional weight. Accordingly, the method is not suitable.